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Courtesy Patrol Saves Time and Money for Colorado Motorists

A paper prepared for the January 22-28, 1995 meeting of the
Transportation Research Board reported on the success of a
Colorado Department of Transportation (CDOT) pilot program. The
program put courtesy patrols on Denver-area freeways to provide
incident management during rush hours and to attempt to reduce
congestion. CDOT contracted with the University of Colorado at
Denver to evaluate the program. Peggy Cuciti of the University's
Center for Public Private Sector Cooperation and Bruce Janson of
the College of Engineering wrote the resulting report entitled
"Incident Management Via Courtesy Patrol: Evaluation of a Pilot
Program in Colorado." This article describes the courtesy patrol
program and summarizes the evaluation of its effectiveness.

Background

The Intermodal Surface Transportation Efficiency Act of 1991
(ISTEA) encourages state highway agencies to make more efficient
use of existing highways and discourages new highway construction
projects. The challenge is to develop alternate methods of
reducing traffic congestion, especially in areas like Denver,
Colorado, where air quality is out of compliance with national
standards.

Traffic congestion contributes to poor air quality;
moreover, traffic congestion translates into losses for society.
As speeds decrease, trip times increase. Congestion on urban
freeways results in an estimated annual loss of two billion
vehicle hours. Traffic congestion increases fuel consumption.
It also increases collision rates. According to Cuciti and
Janson, the yearly national cost of traffic congestion on urban
freeways is $16 billion.

Congestion is not always the unavoidable result of too many
vehicles for the designed capacity of the freeway. Research has
shown that certain "incidents" on or along the roadway account
for as much as 60 percent of urban freeway traffic congestion.
These incidents include:

(1) major accidents that tie up several lanes or entire
freeways for hours, (2) minor accidents and stalled vehicles
that block only one lane for short durations, (3) vehicles
stopped in shoulders, (4) spilled loads, (5) construction,
utility and maintenance activities and (6) special events
that generate heavy traffic volumes.

The Federal Highway Administration estimates that when an
incident blocks one lane of a three-lane roadway, traffic
capacity reduces by half. Even when the incident is not on the
road (e.g., on the shoulder of the roadway), traffic capacity
reduces by a fourth. The latter capacity reduction results from
the "gawking effect," when people slow to look at an incident.
Clearing the incident from the roadway returns the capacity to
normal; the more quickly this is done, the less congestion
occurs. According to estimates from the California Department of
Transportation, each minute saved in clearing away an incident
yields a reduction in motorist delays of four to five minutes.

History of the Colorado Program

In 1991 the Colorado Incident Management Coalition (CIMC)
began evaluating traffic congestion on Denver-area freeways.
This multi-disciplinary group (composed of agencies and
corporations involved in traffic management and incident
response) found severe traffic congestion during morning and
evening rush hours. Since projections suggest vehicle miles
traveled in the Denver metro area will increase from the present
34 million to 65 million by 2010, traffic congestion problems
will get worse.

Given the expense and political complications of expanding
existing freeways or developing new alternate routes, the CIMC
suggested better incident management as a viable strategy to
improve traffic flow, minimize motorist delays, and reduce air
pollution. The coalition recommended an incident management
program designed "to reduce incident detection and verification
time, reduce incident response time, reduce incident clearance
time, develop effective incident scene management, and provide
timely and accurate information to motorists." Implementation of
the entire comprehensive plan would take time and would require
changes in the law and extensive cooperation among jurisdictions.
The courtesy patrol program, however, was a portion of the plan
that could stand alone and that CDOT could set in motion fairly
quickly.

Courtesy Patrol Pilot Program

The Colorado courtesy patrol pilot program involved both the
Colorado State Patrol (CSP) and the American Automobile
Association (AAA) in delivering services. The program also
enlisted the cooperation of various organizations. Metro Traffic
Control and commercial media helped with communications. The
Denver Police Department coordinated with program personnel on
traffic law enforcement and emergency response services. Private
businesses provided taxi services for stranded motorists and
parking lot space for disabled vehicles.

The pilot program operated six courtesy patrols during rush
hours--from 6:00 a.m. to 9:00 a.m. and from 3:30 p.m. to 6:30
p.m. Monday through Friday. Patrols covered about 27 miles of I-
25 and a short section of I-70 where it intersects I-25. CDOT
chose these times and places because of heavy traffic congestion
and high need for improvement.

CSP used volunteer off-duty officers to cover the six hours
per day, five days a week required for the courtesy patrol. The
officers received time-and-a-half pay for the work. AAA adjusted
schedules and staffed courtesy patrol units with their regular
drivers working for regular wages. Personnel received briefing
on the procedures and responsibilities of the courtesy patrol.
No other training beyond that provided by CSP and AAA to their
own personnel was deemed necessary.

During the designated times, two patrol units operated in
each of three zones established on the freeways. CSP provided
two units, and AAA provided four. Their responsibility was "to
assist disabled vehicles that are blocking lanes of traffic or
are on the shoulder of the roadway." Although units sometimes
helped at collision sites, their emphasis was on non-collision
incidents.

Types of Problems

During the six months from August 28, 1992 through February
26, 1993, the courtesy patrol wrote up 3,393 incidents--an
average of 27.6 incidents each day the patrol was on duty. About
28 percent of these incidents resulted from flat tires, running
out of gas, and radiators overheating. Another 22 percent of
responses were for abandoned vehicles, a problem the patrol could
do relatively little to correct. Other incidents included:
miscellaneous mechanical problems (34 percent), collisions (9
percent), debris on the road (1 percent), and miscellaneous other
(6 percent). The "miscellaneous other" category incorporated a
variety of causes, including some that involved the driver rather
than the vehicle (e.g., the driver pulled over to read a map or
use a cellular telephone).

Cars made up 61 percent of vehicles involved in incidents,
and pickup trucks or vans accounted for an additional 29 percent.
The rest were buses, trucks, or vehicles with trailers--larger
units that presented more difficulty for the patrols if they had
to be moved.

Slightly more incidents happened on Mondays and Tuesdays
than on Thursdays and Fridays, and 55 percent of reported
incidents happened during afternoon rush hours. Involved
vehicles were not blocking a lane of traffic in 72.7 percent of
the incidents. Vehicles were found on the right shoulder rather
than the left in 63 percent of the cases. The incidents most
likely to result in vehicles blocking traffic lanes were
collisions and mechanical problems.

Courtesy patrol personnel located about 90 percent of the
incidents themselves, while Metro Traffic Control supplied the
rest of the leads. When patrol personnel had to respond to
information from an outside source, it took seven minutes on
average for a patrol vehicle to arrive at the scene.

Types of Services Rendered

To fulfill their mission of decreasing the time involved in
clearing an incident from the roadway, courtesy patrol personnel
were prepared to provide certain services immediately. The
authors noted that courtesy patrol staff were:

. . . prepared to fix flat tires, provide a free gallon of
gasoline, fill radiators with water, jumpstart stalled
vehicles and fix some other minor mechanical problems. If
vehicles ha[d] more serious or difficult-to-identify
mechanical problems, the courtesy patrol [could] move the
vehicle or call for other assistance.

In addition, patrol personnel would use emergency lights to
protect an incident scene.

In 14 percent of incidents, motorists refused courtesy
patrol service, because other assistance was on the way or the
motorist felt the incident was under control. When the patrol
did render assistance, they would sometimes, for example, push a
vehicle out of a traffic lane and then provide gasoline.
Therefore, the average motorist received more than one type of
assistance. The patrol reported providing an average of 1.16
services per incident.

Courtesy patrols helped in the following ways: fixed flat
tires in 72 percent of those incidents; provided a gallon of gas
to 81 percent of vehicles in need; directly serviced overheated
radiators in 51 percent of cases; rendered miscellaneous
mechanical service to 20 percent of disabled vehicles; cleared
debris 87 percent of the time, protected the scene of a collision
in 66 percent of cases; and pushed or towed disabled vehicles
about one-fifth of the time.

As an average for all vehicles, it took the courtesy patrol
9.9 minutes to move a disabled vehicle from the traffic lane.
The average time for moving vehicles that were able to resume
travel on their own was 8.6 minutes, while vehicles needing to be
pushed or towed took 12.7 minutes.

According to information provided by courtesy patrol
personnel, they "cleared" 80 percent of the incidents to which
they responded. This figure does not include abandoned vehicles.

Effectiveness of the Courtesy Patrol Pilot Program

Four phases make up the total amount of time elapsed from
the occurrence of an incident that causes traffic congestion to
the return of normal traffic flow. The detection phase is the
time from when the incident happens until someone who can respond
learns about it. The response phase is the time it takes for
someone to arrive at the scene. The service phase is the time
elapsed from the arrival of assistance until the incident is
sufficiently cleared so that normal traffic capacity exists. The
queue dissipation phase (also called traffic restoration time) is
the time it takes, once capacity has been restored, for traffic
to begin moving normally for that location at that time of day.

Vehicle delays will vary with the amount of time involved in
each of these phases for a particular incident. Traffic volume
at the location during the incident will also affect delay times
and will hinge on the availability of alternate routes for
vehicles approaching the incident. In addition, the number of
lanes blocked and the number of lanes open to go around the
blockage influences the congestion caused by an incident.

Using industry formulas to compare estimated traffic delays
caused by an incident when the courtesy patrol was in operation
and when it was not, this research attempted to determine to what
extent operating the courtesy patrol decreased traffic
congestion. To learn the average length of time it took for an
incident to be detected and cleared before the courtesy patrol
came on the scene, researchers used data from Metro Traffic
Control, a private company that collects traffic data for Denver
television and radio stations.

Metro Traffic Control had no information on the average time
required after an incident happened to notify someone who could
respond. Although the authors felt response times were faster
when six courtesy patrol units were cruising the area looking for
incidents, they lacked comparative data to include in study
results. Therefore, they used an average detection time of 5.5
minutes, the approximate time it took for courtesy patrol
personnel to visually scan all of their assigned zone.
Conclusions about improvements in incident-clearance time assumed
there was no change in the length of time required to detect an
incident with or without courtesy patrols.

Assuming no decrease in detection time, researchers used
available data on response and service times to compare total
incident duration with and without courtesy patrols in operation.
Courtesy patrols cleared incidents blocking a lane of traffic an
average of 10.5 minutes faster than comparable incidents were
cleared without courtesy patrol units on duty. For incidents
that did not block a lane, average incident duration time
decreased by 8.6 minutes.

Researchers then computed the time savings for motorists
represented by shorter incident durations. Computations based on
high estimates of traffic volumes and lengths of vehicle delays
for various types of incidents led the researchers to conclude
that the courtesy patrol saved an average of 98 vehicle hours of
delay for each morning incident they cleared and 75 hours of
delay for each afternoon incident. Using low estimates, the
savings dropped to 78 vehicle hours for morning incidents and 71
for afternoon incidents.

The final computation allowed evaluation of the courtesy
patrol's cost effectiveness--determining how much money the
program saved compared to the expense involved in running it.
Here researchers used an average figure for the value to society
of each hour saved by getting people and goods moving more
quickly. That average is $10 per vehicle hour. Based on high
estimates of the decrease in hours of motorist delay, the program
saved approximately $2,027,850 by reducing motorist delays.
Based on the low estimates, the savings was about $1,757,930.
The authors pointed out that these figures did not include the
direct savings motorists gained when they received services that
solved their problems without having to pay for towing or repair.

The estimated cost of operating six courtesy patrol units
for six months was between $120,000 and $168,000. The low figure
used AAA costs for all six units, and the high figure used CSP
costs. AAA costs were lower because they paid regular wages
rather than the time-and-a-half wages paid by the CSP to off-duty
personnel. The low figure assumed that if this pilot program
were implemented on a regular basis, it would be staffed by
personnel receiving wages lower than the $31/hour paid to off-
duty CSP personnel.

Using either cost figure, the return on society's investment
in this courtesy patrol program would be good. At the low end,
the program returned $10.50 for every $1.00 spent. At the high
end, the return was $16.90 for every $1.00 spent.